Shortly after midnight on Friday, Sue Stanhope, the counting officer for the city of Sunderland, will declare how many people in that area have voted for the United Kingdom to leave the European Union, and how many have voted for it to remain. It will be among the first of 382 such declarations – one for each local authority area in Great Britain – with additional results for Northern Ireland and Gibraltar. Further reports will follow at uneven intervals throughout the night: the last are not expected much before seven in the morning.

These declarations will flesh out a picture which is already clear in broad outlines – a country where Scotland and London will vote to Remain, and where the east of England and the Midlands will just as reliably vote to Leave, but where Wales hangs in the balance; a country where major cities vote to stay in by margins of two to one, and where the countryside opts out; a country where university towns such as Oxford, Cambridge and Durham will deliver lopsided tallies for Remain, just as the working class areas which surround them dally with Leave.

Yet these declarations – which will subsequently be tallied at regional and national level – will be much more consequential than the constituency outcomes of last year’s general election, for two reasons. First, this is a national contest rather than a series of local contests. What matters in each area is not just which side won, but how many votes they banked along the way. Second, there will be no exit poll for this referendum. The techniques used for general elections do not work when applied to events such as this. The only way of projecting the likely outcome is to interpret the results as they arrive.

This poses a problem. Unlike in a general election, we cannot compare a party’s performance in an area with how they did five years ago. How then are we supposed to know what constitutes a good, bad or indifferent result for each side in each area?

Surveys provide one answer, and in particular the large academic surveys of the type carried out by the British Election Study team. After last year’s election, it contacted almost 30,000 people, asking them how they voted in the general election, how they might vote in an EU referendum, and what local authority they lived in.

This survey isn’t enough on its own. With on average 80 respondents in each area, the margins of error – the uncertainty surrounding our best guesses of the proportion of people in each area who would vote to leave and to remain – are very large. We need to combine this survey information with information about the characteristics of each area – and in particular the types of people who live there.

In 1975, at the time of our last referendum on Europe, men who left school without any qualifications but who were in full-time work could expect to earn around three-quarters of the median salary. Now, men in that same category can only expect to earn two-thirds of the median. Older men and women without educational qualifications are very likely to vote for Britain to leave the EU – not because they’re stupid or uninformed but because over the past 40 years their relative position within society has worsened.

Unsurprisingly, this means that areas with lots of older voters, and voters with lower educational qualifications, are more likely to vote Leave. Urban areas, which tend to attract younger, better qualified residents, are more likely to vote Remain.

This explains why London is so europhile, and why there are so many “littoral leavers” – the very many older residents of the forgotten seaside towns that stretch along the east of England from Clacton to Skegness. How does this help us with Sunderland? By incorporating this extra information into a model of how people vote, we can get useful estimates of the proportion of people in each area who would vote to leave. These “absolute” levels aren’t so useful – the survey dates back to last year, when opinion on the EU was very different. But we can shift these estimates up or down to imagine what would happen if the referendum were essentially tied.

If the referendum were a dead heat, we should expect Leave to be six percentage points ahead in Sunderland, winning 53% to 47%. That figure is still subject to a lot of uncertainty: in a dead heat Leave could be anywhere between one point behind and 13 points ahead. But the closer things are in Sunderland, the better things will be for Remain.

Early declarations in London will give a very different picture. London, together with Scotland and (to a lesser extent) Wales, will give Remain its most reliable votes. Wandsworth is one of the first areas in London expected to report. If the referendum is tied nationally, I would expect more than two-thirds of Wandsworth voters to back Remain – but again this figure might easily be four or five percentage points lower or higher.

This maddening uncertainty is heightened by the role of turnout. Generally, higher turnout is expected to favour Remain. As turnout rises, younger, Remain-supporting voters are drawn in, tilting the balance in favour of the status quo. However, higher turnout nationwide might conceal important regional variations.

There have been suggestions that voters in Scotland might be suffering from referendum fatigue, and might therefore be less likely to turn out and vote. When the national result is announced sometime on Friday morning, I expect that many of us may also feel fatigued, not just because we have watched results come in through the night, but because we have witnessed a referendum campaign that has been more rancourous and tragic than any of us could reasonably have expected.

Chris Hanretty is Reader in Politics at the University of East Anglia

What to expect

12.30am

Sunderland reports. Expect Leave to have a lead of six points if the national vote is tied. Sunderland will be followed by Wandsworth and the City of London, most likely reporting huge leads for Remain.

A slow trickle of results will keep the broadcasters occupied. Newcastle and Hartlepool will illustrate the difference between big cities and towns. Remain will hope to have a double-digit lead in Newcastle, but will rightly fear a big loss in Hartlepool.

2am

The first big wave of results, with 22 councils expected to declare at or around this time. Worth keeping an eye on Wrexham, one of the more Eurosceptic parts of Wales, which would be close if the national result is close.

2.30am

Castle Point in Essex – one of the most Eurosceptic authorities in the country, and an area in which Ukip has often done well – declares around this time. Perhaps more useful as a signpost are the two Welsh declarations expected about now – Swansea and Caerphilly. Caerphilly, in particular, is likely to be finely balanced between Leave and Remain.

3am

By this point, we’ll be roughly two-fifths of the way there. A key area to focus on is City of Lancaster, which will probably vote the same way as the rest of the UK.

3.30am

Edinburgh reports along with Aberdeen, Dumfries and a number of other Scottish local authorities. Edinburgh is tipped by Ladbrokes to have the highest vote in favour of Remain, so the outcome isn’t in doubt, but turnout might be important.

4am

The motherlode – 88 areas are expected to report at around this time. It may be at this point that broadcasters start considering whether to make a projection.

5am

By now roughly nine out of 10 areas should have reported. The remainder are mostly rural areas which lean towards Leave, sometimes quite heavily.

6am

If no projections are forthcoming by this point, the referendum may be achingly close. Sefton, expected to report about now, is one of a number of Labour-leaning areas in Merseyside that might disappoint the Labour party by very narrowly voting to leave.

7am

The last batch of areas to report. Most of these favour Leave, Arun in West Sussex and Waveney in Suffolk particularly so. If the result is still not known by this stage, it is almost certain that some constituent parts of the UK have voted to leave the EU while others have voted to remain, opening up a constitutional crisis lasting far beyond Friday morning.